Simplify the following expression: $n = \dfrac{-9}{3q} - \dfrac{9}{3q}$
Explanation: Since the expressions have the same denominator we simply combine the numerators: $n = \dfrac{-9 - (9)}{3q}$ Combine like terms: $n = \dfrac{-18}{3q}$ Simplify by dividing numerator and denominator by 3: $n = \dfrac{-6}{q}$